Geographic Range
Historically,
Diceros bicornis
has been distributed throughout Africa, south of the Sahara, with the exception of
the Congo Basin. The current range of black rhinoceroses is bounded by Cameroon, Kenya,
and South Africa but their distribution within those limits is fragmented.
Habitat
Black rhinoceroses live in various habitats that range from deserts to grasslands,
both tropical and subtropical. They are also present in African forests, especially
in areas where grasslands and forests phase into one another. Black rhinos generally
stay within 25 kilometers of water.
- Habitat Regions
- temperate
- tropical
- terrestrial
- Terrestrial Biomes
- desert or dune
- savanna or grassland
- scrub forest
Physical Description
Although the color of black rhinoceroses can vary from yellow-brown to dark-brown,
the general color is grey. Specific skin color depends on the soil conditions within
the habitat of each individual. The skin is naked or hairless, with the exception
of short, fringe-like hair on the short and rounded ears. On average, black rhinos
have a shoulder height between 1.4 and 1.8 m, a head and body length between 3 and
3.75 m, and a weight between 800 and 1400 kg. Tail length is generally around 0.7
m. Although similar in size, males are normally a little larger than females.
Black rhinos have two horns, one posterior and one anterior, which are made from keratin
instead of bone. The anterior horn is normally longer, measuring 42 to 128 cm, while
the posterior horn is 20 to 50 cm. In some cases, black rhinos have a third, posterior
horn, which is small. Females tend to have longer and thinner horns than males.
The trait that distinguishes black rhinos from
white rhinos
is the pointed, prehensile upper lip found in black rhinos, as opposed to the square
lips found in white rhinos. This lip is used to pick up food such as twigs. Additionally,
black rhinos have smaller heads, shorter ears, and shorter horns than white rhinos.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
- male larger
- sexes shaped differently
- ornamentation
Reproduction
Adult black rhinos are typically solitary creatures. However, during mating, black
rhino adults come together. Black rhinos are polygynous. Male rhinos begin a courtship
by following females, including their dependent offspring, for approximately one or
two weeks before mating actually begins; even while sleeping, the male and female
remain in contact with one another. Males exhibit certain behavioral characteristics
before mating: they walk in a stiff-legged manner and brush their horns along the
ground in front of the female. Before copulation begins, many attempts by the male
to mount the female are made; if the female is not yet ready, she will make a series
of attacks or charges at the male. When insertion is actually achieved, copulation
lasts between 20 and 40 minutes. If the mating is unsuccessful, females return to
a state of heat within 35 days of the previous copulation.
- Mating System
- polygynous
Breeding occurs throughout the year but peak breeding season varies by location. Gestation
lasts approximately 15 months. Females give birth to one offspring at a time, which
usually weighs between 20 and 25 kg. Weaning of offspring typically occurs after 18
months, but offspring remain dependent for up to 4 years. Females achieve sexual maturity
at age 5 to 7 years; males reach maturity between 7 and 8 years.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
For the first week after birth the offspring is hidden by the mother. After that,
the mother and calf use specific vocalizations to find one another: the mother pants
and the calf squeals. Black rhino mothers are very protective of their calves, which
is why calves walk behind their mothers. This differs from white rhino females, who
have their young walk in front of them. Calves are able to browse on their own after
one month and able to drink water after 4 to 5 months. Black rhino offspring aren’t
weaned until 18 months; after that, the calf remains dependent on its mother for up
to 4 years. The basic social unit for females is typically a female and her young
offspring, until the offspring is forced into independence by a sibling.
- Parental Investment
- precocial
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
protecting
- female
-
protecting
Lifespan/Longevity
Typical lifespan in the wild is between 30 and 35 years, with little expectation of
exceeding 35 years. In captivity, black rhinos can live over 45 years, with the record
being 49 years. Factors that limit lifespan in the wild include poaching for horns
and habitat fragmentation.
Behavior
Typically, black rhinos are relatively solitary. Males remain solitary until it is
time to mate; females reside with their young offspring in a solitary family unit.
There are exceptions, as females without young sometimes associate with other females.
The largest black rhino group that has been observed so far has been made up of 13
rhinos, but this was a temporary association.
Black rhinos have a sedentary lifestyle and remain in one general area. They are less
active during the middle of the day, using mornings and evenings to eat, drink, and
move around. When they are startled, they tend to run away from the source. While
fleeing, rhinos issue a series of snorts and curl their tails until they calm down.
Once the initial scare has passed, the rhino’s curiosity kicks in, and it will examine
the source with inquisitive charges. Even though there is severe danger associated
with black rhino charges, the charge normally does not end with serious consequences.
In order to remain cool during especially hot times of the day or season, black rhinos
roll in mud to get it all over their bodies. They also make trips to local salt licks
to get needed nutrients necessary for survival.
Adult black rhinos defecate on dung piles as a means of communication, as it reveals
to other rhinos how recently an individual was in a certain location. Males also
use their feces to mark territories; they kicking their feces to get fecal material
on their feet, then move around their home range. They also urinate to mark their
home range.
When two females meet, they demonstrate little aggression, merely approaching each
other and possibly nudging each other with their horns, and then retreating. However,
when two males or a male and a female meet, more aggression is exhibited. Upon meeting,
a male and female interact in the way described the above. When two males meet, however,
violence can very easily ensue. Many times, the less dominant of the two retreats.
If not, the males charge at one another, horn first and groaning loudly. The anterior
horn provides the rhinos with a very effective weapon during the interaction.
- Key Behaviors
- terricolous
- diurnal
- motile
- sedentary
- solitary
- territorial
Home Range
There is large variation in home range size of black rhinos. Depending on region and
habitat, home range can range from 2.6 km^2 to 133 km^2. Habitats with better conditions
generally result in smaller home ranges, while poorer conditions result in larger
home ranges, presumably because rhinos have to travel further to acquire food and
water.
Black rhinos are not excessively territorial within their home ranges, but dominant
males are more likely to express territorial behavior against other dominant males
than females and males lower down in the hierarchical system.
Communication and Perception
Although black rhinos use vision, acoustic, and smell senses, their sense of smell
is what they rely on most. They have poor vision, with the ability to see only 25
to 30 m away. Their sense of hearing is good, but not up to the level of their sense
of smell.
Black rhinos use the pheromones and scents from their feces and urine to mark territories.
Additionally, they engage in calls to one another that can take the form of the pant-squeal
interaction seen in mothers and their infants to loud roars that signify aggression.
When a subordinate male enters the territory of a more dominant male, the combination
of calls and territorial scents causes the subordinate male to retreat.
- Other Communication Modes
- pheromones
- scent marks
Food Habits
Black rhinos are browsers that feed on items such as twigs, woody shrubs, small trees,
legumes, and grass. Black rhinos show a preference for
Acacia
species, as well as plants in the family
Euphorbiaceae
. They eat an average of 23.6 kg during the course of each day.
Black rhinos use their characteristic prehensile upper lip to grab plants and guide
them into their mouths, where their cheek teeth can do the rest of the work. In addition,
black rhinos use their horns to gain access to higher branches by breaking or knocking
down plants. Scraping bark off of trees is also part of the repertoire of black rhino
feeding.
- Plant Foods
- leaves
- wood, bark, or stems
- seeds, grains, and nuts
Predation
Humans,
Homo sapiens
, are the most important predator of black rhinos; however, both lions (
Panthera leo
) and spotted hyaenas (
Crocuta crocuta
) sometimes prey on young rhinos. Lions also sometimes attack adults. Black rhinos
use their size and strength as a defense mechanism by charging at their predators
both to threaten predators and actively defend themselves and their offspring.
Ecosystem Roles
Black rhinos and oxpeckers (
Buphagus
species) are involved in a mutualistic relationship where the oxpeckers eat parasites
taken from the rhino’s skin. Additionally, oxpeckers are able to warn rhinos of approaching
predators because their vision is much better than the rhino’s vision.
Black rhinos are significant herbivores and influence plant communities.
- Ecosystem Impact
- disperses seeds
- oxpecker ( Buphagus africanus )
- oxpecker ( Buphagus erythrorhynchus )
Economic Importance for Humans: Positive
Black rhinos have the potential to help create awareness for conservation efforts.
Additionally,they provide educational value both through biology and through art.
Black rhino horns are also very valuable for their use in various products, such as
traditional Chinese medicine and traditional Yemen dagger handles. The popularity
of their horns is a major reason why the species as a whole is in trouble.
- Positive Impacts
- body parts are source of valuable material
- source of medicine or drug
- research and education
Economic Importance for Humans: Negative
Although many charges by black rhinos towards humans and their vehicles turn into
innocent advances, some may cause injury or death to humans, or damage to vehicles
that results in monetary loss.
- Negative Impacts
- injures humans
Conservation Status
Black rhinos have been on Appendix I of CITES since 1977. Additionally, black rhinos
have been listed since 1980 under the United States Endangered Species Act. Black
rhinos are listed as critically endangered by the IUCN Red List.
Currently, there are four subspecies of black rhinos:
D. bicornis bicornis
,
D. bicornis longipes
,
D. bicornis minor
, and
D. bicornis michaeli
. The first subspecies is listed as vulnerable on the IUCN 2008 Red List, and the
latter three are all listed as critically endangered.
Conservation efforts to preserve black rhinos include establishing a ban against the
horn trade, creating fenced sanctuaries for black rhinos to better protect them from
poachers, and dehorning black rhinos to decrease incentive for poaching. With these
efforts, the total population of 2,400 black rhinos towards the end of the twentieth
century increased to 3,100 black rhinos by 2001.
Additional Links
Contributors
Jennifer Kurnit (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual ornamentation
-
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
- polygynous
-
having more than one female as a mate at one time
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- young precocial
-
young are relatively well-developed when born
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- drug
-
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
References
Berger, J. 1994. Science, Conservation, and Black Rhinos. Journal of Mammalogy , 75(2): 298-308.
Brooks, M. 2002. "Black Rhinoceros (Diceros bicornis)" (On-line). Arkive. Accessed April 09, 2009 at http://www.arkive.org/black-rhinoceros/diceros-bicornis/info.html .
Convention on International Trade in Endangered Species of Wild Fauna and Flora, 2009. "CITES-listed Species Database" (On-line). Accessed April 09, 2009 at http://www.cites.org/eng/resources/species.html .
Dollinger, P., S. Geser. 2008. "Black Rhinoceros" (On-line). World Association of Zoos and Aquariums - Virtual Zoo. Accessed April 09, 2009 at http://www.waza.org/virtualzoo/factsheet.php?id=118-003-003-001&view=Rhinos&main=virtualzoo .
Garnier, J., M. Bruford, B. Goossens. 2001. Mating system and reproductive skew in the black rhinoceros. Molecular Ecology , 10: 2031-2041.
Garnier, J., W. Holt, P. Watson. 2002. Non-invasive assessment of oestrous cycles and evaluation of reproductive seasonality in the female wild black rhinoceros (Diceros bicornis minor). Reproduction , 123: 877-889.
Grzimek, B. 2005. "Black Rhinoceros" (On-line). Answers.com. Accessed April 09, 2009 at http://www.answers.com/topic/black-rhinoceros-1 .
Hillman-Smith, A., C. Groves. 1994. Diceros bicornis. Mammalian Species , 455: 1-8.
IUCN Species Survival Commission, 2008. "IUCN 2008 Red List" (On-line). Accessed April 09, 2009 at http://www.iucnredlist.org .
Lang, E. 1983. "Diceros bicornis" (On-line pdf). CITES. Accessed April 09, 2009 at http://www.cites.org/eng/resources/ID/fauna/Volume1/A-118.003.003.001%20Diceros%20bicornis_E.pdf .
Massicot, P. 2006. "Black Rhinoceros" (On-line). Animal Info. Accessed April 09, 2009 at http://www.animalinfo.org/species/artiperi/dicebico.htm#Weight .
Morgan, S., R. Mackey, R. Slotow. 2009. A priori valuation of land use for the conservation of black rhinoceros (Diceros bicornis). Biological Conservation , 142: 384-393.
U.S. Fish and Wildlife Service, 2009. "Endangered Species Program" (On-line). Accessed April 09, 2009 at http://www.fws.gov/endangered/ .
World Wildlife Fund, 2004. "WWF Factsheet: Black Rhinoceros - Diceros bicornis" (On-line pdf). Accessed April 09, 2009 at http://assets.panda.org/downloads/ecop13blackrhinofactsheet.pdf .